Resonance Indicator Pictures:

Images shown are originally from N.E.D.: http://ned.ipac.caltech.edu/

To make the resonance features prominent, I enhanced the images. This involved a combination of inverting the image, cropping the image, enhancing the contrast, and sometimes enlarging the image.

Star Formation Ridge: NGC 5248

Bar: NGC 1300

Arm Spurs: NGC 628

Inner Ring: NGC 1433

Evidence of a three-arm mode? NGC 6946